🚀 go-pugleaf

In article <1992Aug5.095902.57866@cc.usu.edu> sl8nl@cc.usu.edu writes:
>
>I've had no luck reaching my display speeds of 13h.  I've even gone right
>down to storing each plane together, making sure that the size of the image
>is always word-aligned (for rep stosw), making sure that the starting X 
>coordinate starts on a multiple of 4, and making sure that the total X size
>of the image is a multiple of 4.  My speeds still won't compare.
>
>OK, everyone else, lets hear your ideas on this.  I need to be convinced 
>that I can pull it off.

Sorry for popping in in the middle of discussion and without a clear
knowledge of what exactly are you comparing, but I have some information
regarding the speed differences of mode 320x400x256 and mode 13h.

Background: I am working on a 3D space game that uses 256-color shaded
polygons, among other things. I have a viewport on the screen (256x240
pixels on 320x400 mode and 256x122 pixels on mode 13h). I need to clear
this viewport and draw all the polygons on it during every frame. My
320x400 mode uses double-buffering, naturally, and mode 13h uses a separate
256x122 memory buffer which is then copied to screen (rep movsw).

I have found that in this situation the 320x400x256 mode is MUCH faster.
On my 486/33 machine I can reach around 50 frames/sec in that mode, where
mode 13h (although it has only half the number of pixels to update) runs
at less than 30 frames/sec. The speeds may seem slow, but that is because
my game plays digitized four-channel tracker music in the background at
the same time, and the polygon boundaries are anti-aliased in real time.

I think the speed difference is a direct result of the ability to clear
or draw 8 pixels per one STOSW or MOVSW instruction on 320x400 mode,
where it only draws 2 pixels on mode 13h. Very important.

Was this what you were comparing?

Patrick Aalto
ap@tukki.jyu.fi

Ps. I also support S3 86C911 graphics processor in 800x600x256 mode.
With it (viewport size is a huge 640x400 pixels) I can reach around
32 frames/second, and the game is visually absolutely stunning! Compared
to this the old mode 13h looks like a collection of big LEGO blocks.
Awfull!